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Old 11-08-2020, 10:58 AM   #1
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1985 34.5' Airstream 345
Oceanside , CALIFORNIA
Join Date: Sep 2019
Posts: 17
Upgrading to 50 amps

Hello classic MH forum members.
I'm in the process of renovating my 85/86 345.
My current project (no pun intended) is to upgrade the electrical system to accommodate accepting power from a 50 amp source. In addition to replacing the 30 amp land line with a 50 amp cable, I need to add a fourth slip-ring to the cable reel. This fourth slip-ring will allow connection of the second 120 VAC circuit from a 50 amp pedestal. Changes to the switch-over relays (energized when the generator is running to switch the coach power from the land line to the generator) will also need to be addressed.
I contacted the manufacturer of the cable reel (AERO-MOTIVE Model RVA-25AT) but no joy so far with acquiring a fourth slip-ring assembly.
Have any of you performed this modification to the cable reel? If so, where did you acquire the fourth slip-ring?
Do any of you have an AERO-MOTIVE cable reel that you are not using and are willing to sell the slip-ring assembly?
This is my first post of a new thread so my plan is to attach some photos of the cable reel nameplate and of what the slip-ring components looks like. If the photos don't show up then I will seek instructions on how to post photos with my next tread.
Looking forward to your feedback and thanks for the knowledge you have already shared with the forum (which I have been devouring for the last several months).
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Old 11-08-2020, 12:16 PM   #2
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I doubt you’d be able to modify the current reel to bigger cable and another conductor. Would it work to do what modern Airstreams do and install a 50amp socket on the outside and carry a cord?

Are you moving to 50a to add a second AC?
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Old 11-08-2020, 06:21 PM   #3
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I didn't know those were expandable, but it looks like it might be.

Those I've seen have either
1. Bought a 50A reel and 50A transfer switch
2. Installed a second 30A cord, and use a Y adapter (I went this route)
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Old 11-10-2020, 08:22 AM   #4
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1985 34.5' Airstream 345
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Smile

Thanks for the feedback.
To address your questions daleyocum;
- the cable reel and connections are accommodating the larger cable (3 #6 wires and 1 #8 wire) without much of a challenge. A potentially limiting challenge is passing the thicker wires from the slip-rings assemblies through the main shaft to the other side of the reel.
- the coach already has two air conditioners. My hope is that when 50 amp power is available I will be able to use that shore power to run both air conditioning units without firing-up the generator.
- installing a separate 50 amp connector and carrying a cord is definitely an option to pursue if this modification is unsuccessful. The need to modify the switch-over relays would still be necessary in either scenario.
To address your feedback Magnet18;
- you may be right about increasing the number of slip-rings. There is space within the reel hub to add a fourth slip-ring to the 4 post (securing the other 3 slip-rings). The limiting factor right now is acquiring the fourth slip-ring.
Gentlemen, do you know what 50 amp transfer switch other have used?
Thanks again for the feedback and I am looking forward to more.
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Old 11-10-2020, 09:33 PM   #5
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Given the wattage involved there’s the potential for significant heat generation from the old slip rings or your additional one if they encounter any extra resistance from corrosion. I’d be reluctant to go down the path of modifying the old retractor. There’s a real fire danger in the making there.
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Old 11-11-2020, 08:40 AM   #6
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If the slip rings are in good shape, how is it more of a risk after modifying than before?

The rig won't suddenly be pulling more than 30 amps, it will still be limited to 30 amps per leg/30 amps per slip ring contact by the breakers inside the RV.
(Be sure to add a 30A breaker on the inlet of your new line, you don't want to rely on the pedestal breaker)
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Old 11-12-2020, 12:27 AM   #7
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You’re correct when everything works.
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Old 11-12-2020, 03:56 AM   #8
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1985 34.5' Airstream 345
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The slip rings are in good condition and will be cleaned prior to reassembly.

Your concern about resistance heating is a valid concern. Upon dis-assembly of the reel I discovered several troubling conditions.
- the green ground wire was detached from the slip-ring assembly
- the PO had spliced in a new 30 amp pigtail, however the splicing was poorly done and the wires slipped out of the crimp fitting with just a slight tug
- the white insulation on the neutral lead had insulation damage (discoloration and melting) due to excessive heat
- I will be upgrading to #8 wire between the slip rings and the terminal block on the other side of the reel.

My plan is to continue to use 30 amp protection and rely on the larger current carrying capacity of the 50 amp cables to actually reduce heat due to less resistance to the current flow.
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Old 11-12-2020, 05:03 AM   #9
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Quote:
Originally Posted by RETIREDRIVER View Post
.........
Gentlemen, do you know what 50 amp transfer switch other have used?
Thanks again for the feedback and I am looking forward to more.

More info on the subject in Daniels thread:
https://www.airforums.com/forums/f31...ml#post2343573
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